The aircraft travelled 380 feet before making the first solid impact with the ground. Allowing for the descent to be in free fall, the time taken to hit the ground would be roughly 1-1/2 seconds.

Uh oh... you assume no vertical velocity at RR embankment? I give the vertical vector a value of 2000 fpm. At Impact.

The angle of Bank and the lack of lift did not begin at RR impact.

You assume no vertical velocity at the tracks? The a/c also accelerated radially, turning the left wingtip toward Earth at close to the aircraftís horizontal speed, which negates your fuselage centerline as reference. The fuselage did the same. Itís ASPECT relative to the Earth changed, downward, with a component of what had been forward velocity. IOW, its flight path was altered, dramatically, and that changes your very basic calculation? It didnít continue along pointed where it had been.

Falling at one hundred forty feet per second, the Electra should have hit the ground in one half second. Not counting for the added acceleration to which you refer?

That is approximately one hundred feet beyond the impact with the tracks....